The Nervous System Flashcards
What is the central nervous system?
the control centre of the body and is made up of the brain and the spinal cord. The CNS interprets all of the information that is received and sends messages out to the PNS.
What is the peripheral nervous system?
is made up of all the nerves running from and into the spinal cord. Receptors around the body pass information in a wide variety of media such as sight, touch, smell, pain and taste through these nerves into the CNS.
What is the homeostasis?
a constant internal environment which the nervous system and hormones are responsible for. The nervous system maintains the homeostasis by controlling and regulating all parts of the body. A deviation from a normal set point acts as a stimulus to a receptor, which sends nerve impulses to a regulating centre in the brain.
What are motor neurons?
transmit impulses from brain to muscles in order to initiate contractions
What are sensory neurons?
transmit impulses from muscles to brain with feedback on result of contractions
What is isotonic contraction?
the muscle contracts and there is a change in the length of the muscle.
How many type of isotonic contractions are there and what are they?
- Concentric Contraction which is the muscle actively contracts and shortens in length. The origin and insertion of the muscle move towards each other and the angle at the joint decreases. And eccentric contraction which is the muscle actively contracts and increases in length. The origin and insertion of the muscle move further apart and the angle at the joint increases.
What is isometric contraction?
the muscle activates but there is no change in the length of the muscle and therefore no movement occurs. This happens when the force being generated is equal to the force exerted by an object.
What is isokinetic contraction?
the muscle contracts and maintains a constant force throughout the contraction. The speed of the movement is also kept constant. Isokinetic contractions are performed only on particular computerised equipment. This equipment is very expensive and generally used for rehabilitation. It is not possible to perform an isokinetic contraction using free weights or on most resistance training equipment.
What is a motor unit?
a motor neuron that is connected to a number of muscle cells
What are lower motor neurons?
they carry information away from the central nervous system - control skeletal muscle.
What is the all or nothing principle?
The individual muscle fibres of a motor unit will contract to their fullest extent or will not contract at all when stimulated by a motor neuron impulse. It is not possible for the individual fibres of a motor unit to partially contract or to contract one at a time – all must perform a maximum contraction or none will contract.
What are muscle spindles?
are responsible for initiating the stretch (myotatic) reflex by providing feedback on how fast a muscle is stretching/lengthening. They are located within the muscle. Their job is to determine the degree of stretch and to fire motor units in response to the degree of stretch to prevent a muscle from being lengthened too quickly.
What are golgi tendon organs?
provide feedback on the tension applied to muscle tendons. They are located at the junction of muscle and tendon. GTOs work in exactly the opposite way to the stretch reflex, firing in response to severe contraction. This response then inhibits motor unit firing and all contraction ceases and the muscle relaxes. Simultaneously, the antagonist muscle is stimulated to contract.
What are joint receptors?
the joint receptors provide feedback on the angle of a joint and its rate of change. They are located within the joint capsule.
